No, this is not another possible 'Byronic Stone' from the Grotta di Byron. In any case it's unlikely that Lord Byron would have have been inspired by what follows.
This curious occurrence was supposed to have taken place in Scotland, as recorded in the 'Annals of the Parish' by a certain John Galt in 1769 under the title of A Toad Found in the Heart of a Stone.
'I have my doubts whether it was in the beginning of this year, or in the end of the last, that a very extraordinary thing came to light in the parish; but, howsoever that may be, there is nothing more certain than the fact, which it is my duty to record. I have mentioned already how it was that the toll, or trust-road, was set a-going, on account of the Lord Eaglesham's tumbling on the midden in the Vennel. Well, it happened to one of the labouring men, in breaking the stones to make metal for the new road, that he broke a stone that was both large and remarkable, and in the heart of it, which was boss, there was found a living creature, that jumped out the moment it saw the light of heaven, to the great terrification of the man, who could think it was nothing but an evil spirit that had been imprisoned therein for a time. The man came to me like a demented creature, and the whole clachan gathered out, young and old, and I went at their head to see what the miracle could be, for the man said it was a fiery dragon, spewing smoke and flames. But when we came to the spot, it was just a yird toad, and the laddie weans nevelled it to death with stones, before I could persuade them to give over. Since then, I have read of such things coming to light in the Scots Magazine, a very valuable book. Soon after the affair it was referred to as 'the wee deil in the stane'
In a Journal of Travels in England, Holland and Scotland in the years 1805 and 1806, a further reference to this phenomenon is made : 'It is true that small animals, such as toads and frogs, have been occasionally found alive in solid masses of earth or stone, but examples of this kind are extremely rare (...)'.
Eighteenth century doubts about the possibility are expressed here on page 246.
Although 'scientific experiments' have been made by encasing live toads in cemented cavities, the negative results have persuaded the 'biologists' concerned that it's not feasible. Nevertheless, there are enough reports of this uncanny phenomenon to make one wonder. Here are three more examples taken from this particular source, with thanks.
Toad in a stone. 'In 1761, Ambroise Pare, physician to Henry III of France, related the following account to the Annual Register: "Being at my seat near the village of Meudon, and overlooking a quarryman whom I had sent to break some very large and hard stones, in the middle of one we found a huge toad, full of life and without any visible aperture by which it could get there. The laborer told me it was not the first time he had met with a toad and the like creatures within huge blocks of stone.'
Toad in limestone. 'In 1865, the Hartlepool Free Press reported that excavators working on a block of magnesium limestone taken from about 25 feet underground near Hartlepool, England, discovered a cavity within the stone that contained a live toad. "The cavity was no larger than its body, and presented the appearance of being a cast of it. The toad's eyes shone with unusual brilliancy, and it was full of vivacity on its liberation. It appeared, when first discovered, desirous to perform the process of respiration, but evidently experienced some difficulty, and the only sign of success consisted of a 'barking' noise, which it continues to make invariably at present on being touched. The toad is in the possession of Mr. S. Horner, the president of the Natural History Society, and continues in as lively a state as when found. On a minute examination of its mouth is found to be completely closed, and the barking noise it makes proceeds from its nostrils. The claws of its fore feet are turned inwards, and its hind ones are of extraordinary length and unlike the present English toad. The toad, when first released, was of a pale colour and not readily distinguished from the stone, but shortly after its colour grew darker until it became a fine olive brown.'
Toad in a boulder. 'Around the same time, an article in Scientific American related how a silver miner named Moses Gaines found a toad inside a two-foot diameter boulder. The article stated that the toad was "three inches long and very plump and fat. Its eyes were about the size of a silver cent piece, being much larger than those of toads of the same size as we see every day. They tried to make him hop or jump by touching him with a stick, but he paid no attention."
A later article in Scientific American said: "Many well authenticated stories of the finding of live toads and frogs in solid rock are on record."
Image and intro © Mirino. Sources also include A book of Scotland (Collins)